This invention relates generally to an improved control valve for use with pneumatically powered tools. More particularly, but not by way of limitation, this invention relates to an improved control valve apparatus that provides control of the main air flow to the tool motor, venting for quick shut-off, and an override to provide for the resumption of operation.
Control valve apparatus for pneumatic tools, such as drills, cause the drill spindle to move in reciprocating motion (feed and retract), that is, in a direction perpendicular to the longitudinal axis of the drill to accomplish the desired drilling operation. It is necessary to limit such motion and to cause the motion to either stop or change to the other motion to avoid damage to the drill.
Initially, the motion of such tools were partly manually controlled, that is, the drill operator stated started the feed motion, and subsequently stopped the tool when the end of the retract motion was reached. If the operator was not present when the end of the particular motion was reached, damage could occur to the tool.